BI-DIRECTIONAL NOMINAL CURRENT, VARIABLE POWER AND/OR VARIABLE VOLTAGE, ENERGY TRANSFER CIRCUIT

• US 20090302685A1
• Filed: 05/14/2009
• Published: 12/10/2009
• Est. Priority Date: 05/15/2008
• Status: Active Grant

• Current Assignee: IPS Systems Incorporated
• Original Assignee: Indy Power Systems, LLC
• Inventors: Kramer, Quentin Wayne, Tolen, Steve
• Granted Patent: US 8,076,797 B2
• Time in Patent Office: Days
• US Class Current: 307/80
• CPC Class Codes: B60L 50/40 using propulsion power supplied by capacitors
• CPC Class Codes: H02M 3/33584 Bidirectional converters
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

An energy transfer circuit for connecting a load to multiple energy sources that can have different voltages. The energy transfer circuit connects the load and at least two energy sources, and has a control unit. The energy transfer circuit can transfer energy from at least one energy source to the load in response to the load'"'"'s power demand; transfer energy from the load to at least one energy source in response to the load'"'"'s charging current, and transfer energy between the energy sources. The energy transfer circuit also includes a first capacitor in parallel with the primary source and the load; a second capacitor in parallel with the secondary source, an inductor, a first switch between the inductor and the first capacitor, a second switch between the inductor and the second capacitor. The control unit opens and closes the first and second switches in response to the load and sources.

Claims

1. An energy transfer circuit for connecting a load to multiple energy sources, the energy transfer circuit comprising:

a load connection for connecting the load to the energy transfer circuit;

a first source connection for connecting a first energy source having a first voltage to the energy transfer circuit;

a second source connection for connecting a second energy source having a second voltage to the energy transfer circuit, the second voltage being equal to or different from the first voltage;

a control unit for receiving communications regarding the load, the first energy source and the second energy source;

the energy transfer circuit transferring energy from at least one of the first energy source and the second energy source to the load when the control unit receives a power demand from the load, transferring energy from the load to at least one of the first energy source and the second energy source when the control unit receives a charging current from the load; and

transferring energy from either of the first and second energy sources to the other of the first and second energy sources when the control unit determines an energy transfer is necessary.

2. The energy transfer circuit of claim 1, wherein when the control unit receives a highpower demand from the load, the control unit controls the energy transfer circuit to simultaneously transfer power from both the first and second energy sources to the load.

3. An energy transfer circuit for connecting a load to a primary energy source having a first voltage and a secondary energy source having a second voltage, the energy transfer circuit comprising:

a first capacitor connected in parallel with the primary energy source and the first capacitor connected in parallel with the load;

a second capacitor connected in parallel with the secondary energy source;

an inductor;

a first switch between the inductor and the first capacitor;

a second switch between the inductor and the second capacitor; and

a control unit receiving communications regarding the load, the primary source and the secondary source, the control unit controlling the opening and closing of the first switch and the second switch in response to the communications;

wherein the energy transfer circuit enables the primary energy source and the secondary energy source to have different voltages;

enables the load to draw power from either or both of the primary and secondary sources;

enables the load to charge either or both of the primary and secondary sources; and

enables either of the primary and secondary sources to charge the other of the primary and secondary sources.

4. The energy transfer circuit of claim 3, wherein at least one of the first switch and the second switch is a unidirectionally protected switch.

5. The energy transfer circuit of claim 4, further comprising a first diode in parallel with the first switch, the first diode being biased to conduct current from the inductor towards the first capacitor.

6. The energy transfer circuit of claim 5, further comprising a second diode in parallel with the second switch, the second diode being biased to conduct current from the inductor towards the second capacitor.

7. The energy transfer circuit of claim 3, further comprising a third switch between the primary energy source and the load.

8. The energy transfer circuit of claim 3, further comprising a first sensor coupled to the primary energy source and a second sensor coupled to the secondary energy source, the first sensor transmitting communications to the control unit regarding status of the primary energy source and the second sensor transmitting communications to the control unit regarding status of the secondary energy source.

9. The energy transfer circuit of claim 3, wherein the control unit determines the state of charge of the primary and secondary energy sources and controls the transfer of energy between the primary and secondary energy sources using the first and second switches.

10. The energy transfer circuit of claim 3, wherein the control unit receives power demands from the load, and controls the first and second switches to transfer energy from at least one of the primary and secondary energy sources to the load.

11. The energy transfer circuit of claim 3, wherein the control unit receives charging currents from the load, and controls the first and second switches to transfer energy from the load to at least one of the primary and secondary energy sources.

12. A method for transferring energy to and from a load using an energy transfer circuit comprising a first capacitor, a second capacitor, an inductor, a first switch between the inductor and the first capacitor, a second switch between the inductor and the second capacitor, and a control unit, the method comprising:

connecting the load in parallel with the first capacitor of the energy transfer circuit;

connecting a primary energy source having a first voltage in parallel with the first capacitor of the energy transfer circuit;

connecting a secondary energy source having a second voltage in parallel with the second capacitor of the energy transfer circuit;

communicating status information from the primary energy source to the control unit;

communicating status information from the secondary energy source to the control unit;

communicating energy requests from the load to the control unit;

controlling the opening and closing of the first switch and the second switch using the control unit;

responding to charging currents from the load;

responding to power demands from the load;

responding to energy requests for the primary energy source and the secondary energy source; and

keeping the first switch and the second switch open unless responding to the charging currents, power demands or energy requests from the load, the primary energy source or the secondary energy source.

13. The method of claim 12, wherein responding to charging currents from the load comprises:

determining whether either of the primary energy source or the secondary energy source has a charge priority;

charging the primary energy source when the primary energy source has the highest charge priority;

charging the secondary energy source when the secondary energy source has the highest charge priority;

running a trickle charge routine when neither of the primary energy source or the secondary energy source has the charge priority; and

discontinuing the response to the charging current from the load when the charging current ceases; and

discontinuing the response to the charging current from the load after a limited time.

14. The method of claim 13, wherein charging the primary energy source comprises:

keeping the first and second switches open to charge the primary energy source with power from the load.

15. The method of claim 13, wherein the energy transfer circuit further comprises a second diode in parallel with the second switch, the second diode biased to conduct current from the inductor towards the second capacitor, and charging the secondary energy source comprises:

closing the first switch and keeping the second switch open to charge the inductor with power from the load;

then opening the first switch and discharging the inductor through the second diode to charge the secondary energy source;

then repeating these steps at a desired frequency to charge the secondary energy source.

16. The method of claim 15, wherein charging the secondary energy source further comprises the following steps to be repeated as part of the repeating step:

closing the second switch after opening the first switch and discharging the inductor through the second switch to charge the secondary energy source;

then opening the second switch and continuing to discharge the inductor through the second diode to charge the secondary energy source.

17. The method of claim 12, wherein responding to power demands from the load comprises:

determining whether the power demand is a multiple source power demand or a single source power demand;

executing a highpower routine when the power demand is the multiple source power demand; and

executing a single unit power routine when the power demand is the single source power demand.

18. The method of claim 17, wherein executing a highpower routine comprises:

determining whether the primary energy source is in a primary highload operating range;

determining whether the secondary energy source is in a secondary highload operating range;

transferring power from both the primary and secondary energy sources to the load when the primary energy source is in the primary highroad operating range and the secondary energy source is in the secondary highroad operating range;

monitoring the state of charge of the primary and secondary energy sources;

discontinuing the highpower routine when the primary energy source goes outside the primary highroad operating range;

discontinuing the highpower routine when the secondary energy source goes outside the secondary highroad operating range;

discontinuing the highpower routine when the power demand ceases; and

discontinuing the highpower routine after a limited time.

19. The method of claim 18, wherein the energy transfer circuit further comprises a first diode in parallel with the first switch, the first diode biased to conduct current from the inductor towards the first capacitor, a second diode in parallel with the second switch, the second diode biased to conduct current from the inductor towards the second capacitor;

and transferring power from both the primary and secondary energy sources to the load comprises;

providing power to the load from the primary energy source regardless of the positions of the first and second switches;

closing the second switch and keeping the first switch open to charge the inductor with power from the secondary energy source;

opening the second switch and discharging the inductor through the first diode to charge the load;

closing the first switch after opening the second switch and discharging the inductor through the first switch to charge the load;

opening the first switch and continuing to discharge the inductor through the first diode to charge the load; and

repeating these four steps at a desired frequency to charge the load.

20. The method of claim 17, wherein executing a single unit power routine comprises:

determining an operating condition of the primary energy source;

determining an operating condition of the secondary energy source;

transferring power from the primary energy source to the load when the primary energy source is in as good or better operating condition than the secondary energy source;

transferring power from the secondary energy source to the load when the secondary energy source is in better operating condition than the primary energy source;

discontinuing the single unit power routine when the power demand ceases; and

discontinuing the single unit power routine after a limited time.

21. The method of claim 20, wherein the energy transfer circuit further comprises a first diode in parallel with the first switch, the first diode biased to conduct current from the inductor towards the first capacitor, a second diode in parallel with the second switch, the second diode biased to conduct current from the inductor towards the second capacitor;

and transferring power from the secondary energy source to the load comprises;

closing the second switch and keeping the first switch open to charge the inductor with power from the secondary energy source;

opening the second switch and discharging the inductor through the first diode to power the load;

closing the first switch after opening the second switch and discharging the inductor through the first switch to power the load;

opening the first switch and continuing to discharge the inductor through the first diode to power the load; and

repeating these four steps at a desired frequency to charge the load.